Processes of Population Change

The correct answer is A. Population size and population structure are different ideas. Size is the total number of people, whereas age structure describes how that total is divided among children, young adults, middle-aged people and older people. The total can remain unchanged if births and arrivals balance deaths and departures, but the age groups involved may not be equal. For example, many young adults may arrive while older residents leave; the total may stay similar but the share of youth rises. A is correct. B, C and D concern area or physical geography and do not describe age composition. Memory cue: a stable total does not mean a stable population pyramid.

The correct answer is A because it gives the wrong interpretation. Total population change is determined by births, deaths and migration together. A useful expression is: total change = births − deaths + in-migration − out-migration. Births add people and deaths remove people, but movement across places can also alter the population of a particular area. B is correct as a statement because deaths reduce the number of residents. C is correct because in-migration brings people into the area. D is correct because out-migration takes residents away. A is wrong because births are only one component and cannot by themselves determine the total change. Memory cue: never calculate population change from births alone.

The correct answer is A: a decrease of 300. First calculate natural increase: births minus deaths = 2800 − 2100 = 700. Next include net migration. A negative net migration of 1000 means the area loses 1000 more people through migration than it gains. Therefore total change = natural increase + net migration = 700 + (−1000) = −300. The minus sign means a decline of 300 people. B reverses the sign and calls the decline an increase. C gives only the natural increase and ignores migration. D adds the figures without recognising that deaths and negative migration reduce population. Memory cue: positive natural increase can still become total decline when migration loss is larger.

The direct answer is A: births, deaths, migration, and a time period are needed to measure population change. Population does not change only because children are born or people die. People may also enter an area from another place, called in-migration, or leave it, called out-migration. We must compare these changes over a stated period, such as one year, so that the amount and direction of change can be calculated. Option A is correct because it includes the main population processes and the time required for comparison. B describes physical features, not population processes. C describes cultural characteristics; these may help us understand society but do not measure numerical change. D concerns natural resources and production, not the number of people. Memory cue: population change = births − deaths + in-migration − out-migration, measured over time.

The governing concept is the time scale of demographic change. A change is a difference between two measured situations, so the starting and ending dates are essential. Saying that a population increased by a particular amount is incomplete unless we know whether the increase occurred in one year, ten years or a much longer period. Rates and comparisons can be especially misleading when the periods differ. Option A is correct because population change is always interpreted over a stated interval. Option B is false, while C misunderstands migration and D wrongly dismisses deaths, which are part of population change.

The direct answer is A. Rural out-migration means that people, often including working-age youth, leave villages to live or work elsewhere. When many young workers leave, farms, local businesses, and community activities may have fewer available workers. Families may also change: some members remain in the village while others live in a town or city, creating temporary or divided households. A is therefore a possible social effect because it describes changes in people, work participation, and family relationships. B is wrong because people leaving a village cannot make every village immediately double in population; out-migration usually reduces or slows population growth there. C is wrong because migration cannot completely end deaths. D is wrong because out-migration from a village does not guarantee that in-migration will always rise. Memory cue: out-migration means people move out, so think of fewer workers and altered family patterns at the source.

The direct answer is A. Urban in-migration occurs when people move into a town or city from another place. The arriving population needs homes, roads or public transport, drinking water, sanitation, schools, hospitals, and other facilities. Therefore administrators must estimate population growth and expand or improve services. A is correct because it identifies the planning pressure created by additional residents. B is the opposite of reality: more residents generally create more demand for services, not less. C is wrong because people entering a city do not make its population zero. D is wrong because migrants become part of the city’s population and directly affect planning, service use, and sometimes employment and housing demand. Memory cue: in-migration adds people to the destination, so administration must plan for additional needs.

The direct answer is A: the population increases by 400. Solve the two parts separately. First calculate natural change: births minus deaths = 2,500 − 2,800 = −300, so deaths exceed births by 300 and the natural change is a decrease of 300. Next calculate net migration: in-migration minus out-migration = 1,100 − 400 = 700, so migration adds 700 people. Combine the results: −300 + 700 = +400. Thus the final population change is an increase of 400. B gives only the natural change and ignores migration. C gives only the net migration and ignores the excess deaths. D incorrectly adds all four figures, treating deaths and out-migration as additions. Memory cue: total change = (births − deaths) + (in-migration − out-migration).

The direct answer is A. Population change alters the number and composition of people who can work and the number of people seeking jobs. If the working-age population grows, the economy may have a larger labour supply, but it may also face greater demand for employment, skills, and livelihoods. If workers leave through out-migration, local businesses and farms may face labour shortages, while the destination may receive additional workers. These are economic effects connected to population processes. B is unrelated to economic population change and is not a normal result of demographic processes. C is an unsupported physical claim. D is incorrect because population change does not alter the length of a day or the calendar’s number of days. A is correct because it connects population size and age structure with labour and employment. Memory cue: population affects the economy through workers, jobs, and consumers.

The direct answer is A. A growing population usually needs more drinking water, homes, food, roads, energy, and land. It also produces more wastewater and solid waste. If water supply, land-use planning, sewage treatment, and waste management do not keep pace, environmental pressure can become visible through shortages, pollution, congestion, or degradation of land and water. A is correct because it connects a demographic change with realistic resource use and waste-management needs. B is wrong because “the height of the sky” is not a normal measurable environmental effect of population change. C is impossible and unrelated to population geography. D is too absolute and is not a necessary result; soil can be degraded or covered by construction, but it does not simply disappear everywhere. Memory cue: more people mean more resource demand and more waste, unless planning manages them properly.

The direct answer is A. Natural increase is births minus deaths. If births and deaths are equal, natural increase is zero. However, total population also changes through migration. When in-migration is greater than out-migration, more people enter the area than leave it, so net migration is positive. Total change can be written as natural increase + net migration. In this case it is 0 + a positive number, so the total population increases. B would produce negative net migration and reduce the population. C would leave both natural increase and net migration at zero, so there would be no change. D makes natural increase negative because deaths exceed births; unless positive migration offsets it, population would fall. A is therefore correct. Memory cue: zero births-minus-deaths does not mean zero total change; a positive migration balance can still add people.

Answer: A, an increase of 350. Solve the two parts separately to avoid mixing additions and subtractions. First calculate natural change: births minus deaths = 1,800 − 1,800 = 0. Thus births and deaths balance each other. Next calculate net migration: in-migration minus out-migration = 600 − 250 = +350. Finally add the two components: total change = natural change + net migration = 0 + 350 = +350. Therefore the population increases by 350 people. Option A is correct. Option B ignores the positive net migration. Option C gives the wrong direction; the larger number is in-migration, so migration adds people rather than removing them. Option D incorrectly adds births and deaths instead of subtracting deaths and also ignores the migration balance. A useful checking method is to ask: equal births and deaths cancel, then 600 arrivals minus 250 departures leaves 350 arrivals.

Answer: A, zero. The safest method is to calculate natural change and net migration separately. Natural change equals births minus deaths: 1,600 − 1,200 = +400. This alone would increase the population by 400. Net migration equals in-migration minus out-migration: 300 − 700 = −400. This would reduce the population by 400 because 400 more people leave than enter. Now combine them: total change = +400 + (−400) = 0. The increase from births exactly balances the decrease caused by migration. Option A is therefore correct. Option B considers only births and deaths and ignores out-migration. Option C adds quantities without applying the correct signs. Option D notices the migration decrease but ignores the natural increase. Zero total change does not mean no births, deaths or migration; it means the positive and negative effects cancel each other.

Answer: A, an increase of 400. First find the natural increase: births minus deaths = 6,000 − 4,200 = +1,800. Next find net migration: in-migration minus out-migration = 1,300 − 2,700 = −1,400. The negative sign means that 1,400 more people left than entered. Combine the components: total change = +1,800 + (−1,400) = +400. Thus the population still grows, but the migration loss reduces the natural increase from 1,800 to 400. Option A is correct. Option B gives only the natural increase and ignores the migration loss. Option C gives the size of the net migration loss but ignores births exceeding deaths. Option D adds the figures without respecting which processes add and which remove people. Always attach signs before combining: births and in-migration are positive; deaths and out-migration are negative.

The correct answer is A: assuming that internal migration increases the national total population is a scale error. First identify the scale being studied. Internal migration means people move from one part of a country to another, such as from a village to a city. The village loses people and the city gains people, so the distribution changes. However, the country has neither gained nor lost those people because they have remained within its borders. At the national scale, population changes through births, deaths, immigration from another country, and emigration to another country. A is wrong because it confuses a local or regional increase with a national increase. B is correct because international immigration brings people into the country. C is correct because out-migration can reduce a village population. D is correct because in-migration can increase a city population. Memory cue: internal movement redistributes people; international movement can change the national total.

The correct answer is B: the actual population change is 600 people. Use the complete balance equation: actual change = births − deaths + in-migration − out-migration. Substitute the values step by step: births minus deaths is 1200 − 800 = 400, which is the natural increase. The migration balance is 500 − 300 = 200. Add the two balances: 400 + 200 = 600. Therefore the population increases by 600, assuming all figures refer to the same area and time period. A is only the natural increase and ignores migration. C adds or handles one component incorrectly and is not the result of the complete equation. D also does not follow the signs of the four quantities. Remember that births and in-migration add people, while deaths and out-migration subtract people. Memory cue: add the two gains and subtract the two losses, or use the balance formula without changing signs.

The correct answer is B. Migration connects two places, but its immediate population effect is different at each end. The source area is the place from which people leave, so it may lose population, workers or particular age groups. The destination area is the place where migrants arrive, so it may gain population, labour and demand for housing, transport, schools and other services. The effects are not necessarily identical because the two places can have different economies, resources and age structures. A is wrong because the source loses while the destination gains. C is wrong because a source area must have people who can migrate. D is wrong because the destination is directly affected by arrivals. Studying both areas also prevents the mistake of counting the same movement as only a loss or only a gain. Memory cue: every migration flow has two sides—departure at the source and arrival at the destination.

The direct answer is A: the effect may be delayed when the young reproductive-age population is large. A birth-rate-reducing policy can lower the average number of children per woman, but a large number of people are still entering or already in the childbearing ages. Step by step, many couples in this large age group may have children; therefore, the total number of births can remain high for some time even after fertility begins to fall. This delayed effect is called population momentum. A is correct because a large young age group continues to add potential parents. B is wrong because having no children would not describe the usual source of delayed population growth. C is wrong because if births were already zero, there would be no continuing birth effect to delay. D is wrong because mass out-migration is a different process and is not the demographic reason asked here. Memory cue: a young population can keep population growth moving forward like a heavy wheel even after policy slows it.

The direct answer is A. Natural change is calculated from births minus deaths. Actual or total population change also includes migration, which means in-migration minus out-migration. If births and deaths are nearly equal, natural change is small. However, if many people enter the area, the total population can still rise greatly. For example, a natural change of only 100 people plus net in-migration of 2,000 people produces a large actual increase. A is correct because it combines a small birth-death difference with a large positive migration balance. B is wrong because all components are zero, so actual change is also zero. C is wrong because deaths exceeding births and large out-migration would generally reduce the population. D is wrong because equal in-migration and out-migration give zero net migration; by itself this cannot make actual change high. Memory cue: natural change comes from births and deaths; actual change adds migration.

The direct answer is C: the total change is 200. Use the complete formula: total change = births − deaths + in-migration − out-migration. First calculate natural change: 700 − 900 = −200, because deaths are 200 more than births. Next calculate net migration: 500 − 100 = +400, because 400 more people enter than leave. Finally combine them: −200 + 400 = +200. Therefore, the population increases by 200, not decreases. A is wrong because it uses only the negative natural change and ignores migration. B is wrong because the positive net migration does not merely cancel the natural decrease; it is 400, while the decrease is 200, leaving +200. C is correct. D is wrong because it adds the figures incorrectly and does not follow the population-change formula. Memory cue: write two balances separately—births minus deaths, then in-migration minus out-migration—before adding them.

The direct answer is B. Population can grow through natural increase or through migration. Natural increase occurs when births exceed deaths, while migration-based growth occurs when the main addition comes from people moving into the area. In option B, in-migration is high and the birth-death gap is small, so newcomers—not births—are the principal source of urban growth. A is wrong because births far exceeding deaths indicate strong natural increase, and no migration is present. B is correct because it identifies migration as the dominant adding component. C is wrong because high deaths and no in-migration are more likely to reduce the population. D is wrong because zero births and deaths create no natural increase; without migration, there is no stated source of growth either. A useful warning is that urban growth may have both components, but it is called mainly migration-based when migration contributes the larger share.

The direct answer is A. A push factor is an unfavourable condition that encourages people to leave the place of origin. Land pressure in a village can make it difficult for families to obtain enough land or livelihood. A pull factor is an attractive condition at the destination. City employment opportunities can attract people because they may offer work and income. Thus, in A, village land pressure pushes people away while urban jobs pull them toward the city. B is wrong because a lack of opportunities in both places does not provide a clear attractive pull factor. C is wrong because if nobody changes place, the factors have not produced migration. D is wrong because equal births and deaths describe natural change, not push or pull forces. Remember that push and pull factors can operate together; migration is often caused by pressure at the origin plus attraction at the destination, not by only one reason.

The direct answer is B: a falling death rate can produce rapid natural increase when the birth rate remains high. Natural increase is calculated by comparing births and deaths, commonly expressed as birth rate minus death rate; migration is not included. Step by step, if many births continue while fewer people die, the positive gap between births and deaths becomes large. That large gap produces rapid natural increase. A is wrong because a very low birth rate may keep the birth-death gap small even when deaths fall. B is correct because high births combined with fewer deaths create a large positive difference. C is wrong because zero migration does not create natural increase, and zero births cannot produce rapid growth. D is wrong because high out-migration reduces actual population change and is separate from natural increase. Memory cue: natural increase depends only on the birth-death gap; migration belongs to total change.

Direct answer: A, the employability of migrants may remain limited. In-migration means people enter and settle in a destination area. These newcomers may be willing to work, but willingness alone does not guarantee employment. Employers often need particular abilities, such as technical knowledge, literacy, communication, or vocational training. If skill training is weak, many migrants may not possess the skills needed for available jobs. Step by step: high in-migration increases the number of people seeking work; weak training limits their job skills; limited skills can reduce access to stable and well-paid employment; unemployment or underemployment may then increase. A is correct because it describes this human-capital challenge. B is wrong because migration cannot make the death rate immediately zero. C is wrong because it makes an unnecessarily absolute claim and does not describe the employment problem. D is impossible because in-migration adds people rather than making the population disappear. Memory cue: migration brings people, while skills help turn people into productive workers.

Direct answer: A, when many people come to settle in the country. International migration changes the population of a country when people cross a national boundary and live in the destination country. A large inflow can increase demand for schools, hospitals, housing, transport, water supply, sanitation, and employment services. Planners must therefore count the additional population, estimate its needs, and expand or redistribute facilities. The reasoning is simple: international arrivals increase the number of residents; more residents create greater demand; service planning must respond to that demand. A is correct because large-scale settlement can alter both the amount and location of required services. B describes local movement within one village, not international migration. C states that migration is absent, so it cannot show an effect of international migration. D concerns physical drainage and does not directly explain population-service planning. Memory cue: when population moves across a border and settles, planners must plan for the people as well as the place.